PROJECT SUMMARY Male gametes transmit the paternal genome to the next generation. At the same time, they also carry epigenetic information that is passed to the zygote at fertilization. A major unanswered question is whether this inherited epigenetic information influences gene expression, phenotype, and disease susceptibility in offspring. We have found that knocking out the chromatin regulator gene Utx in the mouse male germ line leads to reduced survival and increased rates of tumor formation in offspring, even when offspring do not themselves carry a Utx mutation. This proposal will test the hypothesis that loss of Utx in male germ cells induces epigenetic changes in the gametes that alter gene expression after fertilization and ultimately result in the increased tumor susceptibility observed in offspring. Specifically, the experiments proposed here will examine genome-wide changes in histone modification, DNA methylation, and gene expression in developing and mature male gametes of Utx conditional knockouts (Aim 1); evaluate gene expression and phenotypic effects in embryos of the next generation at the preimplantation and perinatal stages (Aim 2); and define changes in histone modification, DNA methylation, and gene expression in developing and mature germ cells of offspring in order to determine if these changes can persist across multiple generations (Aim 3). The ultimate goal of this study is to understand how changes in the development and gene regulatory state of mammalian male germ cells can impact phenotype and disease in progeny. In the past, this question has been addressed primarily by manipulating the paternal environment using chemical or nutritional exposures, which are difficult to control precisely. In contrast, this study will employ a simple, well-defined and highly reproducible genetic manipulation that can be used to generate germline epigenetic changes. The proposed experiments will elucidate a new mechanism by which epigenetic misregulation in male gametes can contribute to male infertility, a priority area for NICHD. The results will also frame a new mechanism for non-genetic inheritance of disease susceptibility, with broad implications for the etiology and epidemiology of common diseases such as cancer and diabetes.